Efficacy and safety of inhaled fluticasone propionate at doses of 500mcg BID and 1000mcg BID via an MDPI device and placebo BID for treatment of subjects with chronic oral steroid dependent asthma. The study will be evaluated in terms of: the percentage of subjects classified as having changes in daily oral prednisone dose (ie. 100% reduction, 50-99% reduction, 1-49% reduction, no reduction, any increase).